In case of dental prosthesis which are permanently fixed on an implant superstructure there is a growing requirement to employ bridges, crowns which are attached (screwed) in a releasable manner. Straight and/or angle deviation compensating superstructures which can be screwed into the implant by means of which dental devices can be built in the mouth are also applicable for implants where realization of the screw-joint is practically impossible because of the small internal cone angle (1-30°) since the included angle of the implants would be greater after they are built in. As the position of the implants is determined by the jaw-bone, it frequently happens that the divergence of the implants is even greater than 50°. That is often the case that a missing tooth is replaced by means of an implant and the dentist uses a system which cannot be used later as a ‘bridge pier’ fixed by a screw. In some cases in the course of time several type of implants are built in the patient's mouth which would present a problem of compatibility.
U.S. Pat. No. 5,116,225 describes an angulated abutment system for affixing a dental prosthesis to an anchor implanted in the jaw bone such that the dental prosthesis can be mounted axially offset from the axis of the implant. Two components of the abutment system are designed in such a manner to allow the dental prosthesis to be adjusted in small angles of rotation.
The aim of this solution was to make fixing of the superstructure possible from the side of the oral cavity, but the component parts used to this can be produced in a complicated manner. Though the channel is straight, forming the opening is very complicated because of the many intermediate elements.
International patent application WO 2008/138852 describes an adapter for a dental implant with a conical connection recess in its upper part. The adapter comprises a threaded part for connection with the dental implant and a conical main body corresponding to the conical connection recess of the implant, a tool grip portion allowing for attachment of the adapter to the implant by the aid of a tool.
The intermediate part used in this solution is an element provided with outer and inner threads which on the one hand is fixed to the implant and on the other hand the superstructure is fixed in it. Producing of this component part is very difficult and typically it is not used in these days as the superstructure is screwed in the implant directly. Possibly, a suitable interface is installed between the implant and the superstructure in order to ensure correct positioning of the superstructure.
These solutions can be used for adjusting a certain (0°, 15°, 20°, 25°) angle according to a predefined scale of the manufacturer.
U.S. Pat. No. 4,842,518 describes a screw-type implant which can be built in the jaw bone. In order to be able to position the implant at the most advantageous angle, angled abutments for supporting an artificial tooth structure or angularly adjustable abutments are provided.
Swivelling is prevented by frictional force as the fixing screw leans against the spherical shell of the ball and socket joint. The outer surface of the implant is not secured safely.
U.S. Pat. No. 6,358,052 teaches an implant system and method for effecting dental restoration. In a first step the position of the required dental prosthesis is determined, then in a second step this superstructure is worked out.
The implant is screwed in the jaw bone so that it can be adjusted as required to ensure the angle position by means of a ball joint. Then the positioning superstructure can be removed and the permanent superstructure can be produced according to the set position.
Patent application EP 0580945 describes an endo-osseous tooth implant for a fixed dental prosthesis having an essentially cylindrical round body of a metal for implantation in the jaw bone and a metal fastening head for a dental superstructure which can be firmly connected with an implant post. The metal implant post can be screwed into the inner bore which is open at its coronal end of the round body. The round body has on its coronal end a cylindrical annular recess provided with at least one basic body engaging element for reception of a cervical centering collar, provided with at least one spacer sleeve engaging element complementary to the basic body engaging element. The implant post has on its coronal end a partially spherical head which is flattened so as to be essentially plane toward the coronal side and whose diameter is larger than the diameter of an implant post stem located between a cervical threaded section and the partially spherical head.
Patent application EP1621156 also describes an implant system using a pivotal coupling between the implant and the abutment to permit precise angulation in all directions of the abutment.
However, in this solution using additional materials is required as swiveling can be prevented by gluing or welding.
Patent application WO2012/142517 A2 describes a dental implant system which can be used with a special implant family. In this solution the angle can also be adjusted by means of a ball-joint.
Swivelling is prevented by using a cup spring. However, if the spring gets worn out, the implant will be able to swivel and it is difficult to release the screw joint used for fixing. The surface of the upper end of the intermediate piece is ball-shaped on which the superstructure is placed, so it is not supported securely. At the same time it is difficult to block the way from bacteria's getting in.
In some cases the end of the threaded shank is ball-shaped which fits into a ball-shaped seat. When cup spring is used swiveling is prevented by the frictional force not by form fitting. In other cases the ball joint is provided on the upper end of the implant.
Patent application HU 229980 teaches a dental device fixing unit secured resiliently into implants enabling optional angular position adjustment. The fixing unit comprises a threaded shank tiltable in all direction projecting from the implant and a fixing element for securing the threaded shank to the implant. The fixing element consists of an insertion piece and an intermediate piece provided with a bore-hole in which the threaded shank is led through in order to secure the insertion piece to the implant. The end of the insertion piece and the inner end of the threaded shank are attached to each other in a swivelable manner. The inner end of the threaded shank is positioned between the end of the insertion piece and the upper end of the intermediate piece.
In this solution prevention of swiveling of the dental device fixing unit enabling optional angular position adjustment is not ensured by all means when a single tooth must be replaced. In spite of the fact that the insertion piece and the intermediate piece are secured to each other in unreleasable manner, the fixing unit is able to turn aside. If the intermediate piece is not circle symmetric, then the fixing unit cannot be screwed into the implant.
None of the known documents even the combination of them can give a solution for realizing the aim of the present invention.
The aim of the present invention is to improve the teachings of the international patent application WO 2014106761 based on Hungarian patent application HU 229980 in order to prevent the dental device from swiveling by all means, especially when a single dental device is needed to be fixed.